Iraq progressed through to the third round of Asian qualifying for the 2014 FIFA World Cup last week thanks to a 2-0 aggregate defeat of Yemen.
Sidka's charges beat Yemen 2-0 in the first leg, before being held 0-0 - a result that clearly tested the Iraq FA's patience.
Iraq FA Vice-President Abdulkhaleq Masoud said: "We decided not to renew the contract of the coach after the poor results although we qualified for the third round of the World Cup."
Sidka, who assumed his role with Iraq in August 2010, had a contract that was set to run until mid-August. That will not now be renewed, with the Iraq FA set to meet in a bid to find a replacement for the German.
Having qualified for the third round, Iraq were drawn in Group A alongside Singapore, China and Jordan.